The invention is directed to a method for signal transmission in a communication system between a mobile radio and a base station. The invention is also directed to an apparatus for the implementation of this method.
The range in a wireless communication system, for example a cordless telephone, that is composed of a stationary and of a mobile radio transmission/reception means is defined essentially by its transmission power and its receiver sensitivity. The transmission power is thereby usually uniformly emitted in all directions, i.e. nearly spherically, in order, first, to be universally employable in every environment and, second, to achieve the same range in every direction. When, however, an individual is point in time is considered, then--from the point of view of the stationary radio transmission/reception means, i.e. of the base station of the cordless telephone in the example--only a fraction of the transmission energy is emitted in the direction of the mobile radio transmission/reception means, i.e. the mobile part of the cordless telephone in the example. The great majority of the transmission energy, by contrast, is not utilized and can even have an interfering effect on external devices.
A stationary radio transmission/reception means with a sharply bundling direction al antenna would be desirable that emits the available energy concentrated in precisely that direction in which the mobile radio transmission/reception means is situated at the moment. However, a not insubstantial outlay for locating the mobile means, i.e. the mobile part of a cordless telephone in the example, and for the exact alignment of the directional antenna would be required therefor.